The present invention relates to a device for driving an electrical current generator, and more particularly, to a type thereof for use in a motorcycle.
According to a conventional generator system, the generator is disposed within a limited space, so that it would be rather difficult to perform inspection and overhauling. Further, since the system is located within the limited narrow space, sufficient cooling effect therefor would not be obtainable. Furthermore, according to the conventional device for driving an electrical current generator for use in a motorcycle, a V-belt or chain is mounted between a pulley or sprocket secured to an output shaft of an engine and a pulley or sprocket secured to a rotary shaft of an alternating current generator so as to rotate the generator in response to the rotation of the engine. In case of a big motorcycle, an alternator is often employed as a generator. Therefore, the alternator must on one hand supply sufficient electrical current capable of engine ignition even at the low rotation range of the engine such as engine idling range, and must on the other hand keep maximum rotation even at the maximum speed of the engine to provide constant efficiency. Accordingly, the rotation ratio of the rotary shaft of the generator to the output shaft of the engine must be determined within a limited range to meet with both requirements
As shown in broken line in FIG. 4, an output current of the alternator is small at the low rotation range of the engine, particularly at its idling state shown by a region X, so that it would be rather difficult to obtain sufficient electric current charge to a storage battery in case of motorcycle riding at traffic jam condition in night travel during which electrical current for illuminator is particularly required.